U.S. patent number 4,654,706 [Application Number 06/740,376] was granted by the patent office on 1987-03-31 for automatic front of screen adjustment, testing system and method.
This patent grant is currently assigned to International Business Machines Corp.. Invention is credited to William H. Davidson, Ian Miller.
United States Patent |
4,654,706 |
Davidson , et al. |
March 31, 1987 |
Automatic front of screen adjustment, testing system and method
Abstract
This invention relates to a structure to automatically adjust
the image characteristics of a television set or monitor as one of
the final steps in a manufacturing process and a method for
effecting the adjustments and tests which can be practiced by the
structure.
Inventors: |
Davidson; William H.
(Johnstone, GB6), Miller; Ian (Lochwinnoch,
GB6) |
Assignee: |
International Business Machines
Corp. (Armonk, NY)
|
Family
ID: |
24976254 |
Appl.
No.: |
06/740,376 |
Filed: |
June 3, 1985 |
Current U.S.
Class: |
348/190; 348/86;
348/E17.005; 901/47 |
Current CPC
Class: |
H04N
17/04 (20130101) |
Current International
Class: |
H04N
17/04 (20060101); H04N 007/18 () |
Field of
Search: |
;358/139,10,101
;901/47 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Britton; Howard W.
Attorney, Agent or Firm: Frisone; John B.
Claims
Having thus described our invention, what we claim and desire to
secure as Letters Patent is as follows:
1. In an automatic front of screen adjustment and testing system
for automatically adjusting and testing a television monitor an
image acquisition unit comprising:
first means responsive to first positioning signals for viewing a
monitor screen and forming an image of a substantially rectangular
portion of the screen corresponding to the first positioning
signals, said substantially rectangular portion being substantially
less than the total area of the monitor screen;
second means for viewing the image formed on said first means and
converting said image to electric signals corresponding thereto;
and,
third means interposed between said first and second means and
responsive to second signal for adjusting the optical path length
between the second means and the monitor screen to compensate for
path variations which are dependent on the area on the monitor
screen which is being viewed by the third means.
2. An image acquisition unit as set forth in claim 1 in which said
first means comprises:
first positionable means for selectively viewing a narrow
rectangular area on the monitor screen extending between opposite
sides of the monitor screen and forming an optical image
thereof;
second positionable means for selectively viewing a narrow
rectangular area of the image formed by the said first positionable
means.
3. An image acquisition unit as set forth in claim 2 in which said
third means comprises:
an adjustable lens system for focusing the image formed on the said
first means at the said second means.
4. An image acquisition unit as set forth in claim 1 in which said
second means comprises:
a video camera for viewing the image formed at the said first means
and providing an electric signal representative thereof;
a narrow aperture light detecting means for viewing a small area of
the image formed at the said first means and providing electric
signals indicative of the presence of light at the small area
viewed; and,
switching means responsive to third electric control signal for
providing signals from the said camera or the said light detecting
means.
5. An image acquisition unit as set forth in claim 1 in which:
said first means comprises;
a first positionable means for selectively viewing a narrow
rectangular area on the monitor screen extending between opposite
edges of the monitor screen and forming an optical image
thereof,
a second positionable means for selectively viewing a narrow
rectangular area of the image formed by the said first positionable
means and forming an optical image thereof,
said third means comprises;
an adjustable lens system for focusing the image formed on the
first means at the said second means, and
said second means comprises;
a video camera for viewing the image formed on said second
positionable means and providing electric signals representative
thereof,
an aperture light detecting means for viewing a small area of the
image formed on said second positionable means and providing
electric signals indicative of the light intensity of the area
viewed, and switching means responsive to a third electric control
signal for selectively providing signals from said camera and said
light detecting means as a function of the state of the third
control signal.
6. An image acquisition unit as set forth in claim 5 in which the
narrow aperture light detecting means is a photo multiplier
tube.
7. An image acquisition unit as set forth in claim 5 in which the
switching means is a mirror controllable to one of two positions
and which in one position reflects the light emanating from the
first means and in its other position is out of the light path and
said camera is positioned in one path and the light detecting means
is positioned in the other path.
8. An image acquisition unit as set forth in claim 5 in which the
switching means comprises:
a beam splitter positioned in the optical path from the first means
for dividing the light into a first path and a second path and
directing the light in the two paths to the camera and light
detector respectively; and
electric switch means for selecting the electric signals from the
camera or light detector in response to said third electric control
signal.
9. An image acquisition unit as set forth in claim 5 in which:
said first positionable means includes;
a first mirror mounted for rotation on a first motor, the angular
rotation of which is controlled by a first component of said first
positioning signals, said first mirror being arranged to view a
narrow area approximately 1" wide extending horizontally across the
monitor screen and progressing from the top edge to the bottom edge
of the screen as the motor undergoes angular rotation, and said
second positionable means includes;
a second mirror mounted for rotation on a second motor, the angular
rotation of which is controlled by a second component of said first
positioning signals, said second mirror being arranged to view a
narrow area approximately 1" wide extending vertically across the
said first mirror whereby a rectangular image of a small portion of
the monitor screen is present on the said second mirror.
10. An automatic front of screen adjustment and testing system for
automatically adjusting and testing a television monitor
comprising:
a robotic test stand for receiving and holding the monitor being
adjusted and tested, said stand including a plurality of tools for
engaging adjustable electric circuit components of the monitor, and
adjusting said components under control of control signals, a power
supply for energizing the monitor, and circuits for applying
control signals to said tools and video signals to the video input
of the monitor resident in the test stand;
an image acquisition unit positioned proximate the monitor in the
stand, said unit including, first means responsive to first
positioning signals for viewing and forming an image of a
substantially rectangular portion of the monitor screen
corresponding to the first positioning signals, said portion being
substantially less than the total area of the monitor screen,
second means for viewing the image formed on said first means and
for converting said image to electric signals corresponding
thereto, and third means interposed between said first and second
means and responsive to second signals for focusing the image
formed on the first means on the second means to compensate for
variations in the optical path length which are dependent on the
area on the monitor screen being viewed; and
a program controlled processor connected to said robotic test stand
and to said image acquisition unit for sending video test patterns
in the form of video signals and control signals to said robotic
test stand and for receiving the electric signals from the second
means of the said image acquisition unit, said program controlled
processor alternatively providing video and control signals to said
robotic test stand and receiving signals from said image
acquisition unit until the signals from said image acquisition unit
and the video signals supplied to the robotic test stand for
application to the monitor bear a predetermined relationship to
each other or "n" iterative cyles have occurred without achieving
the predetermined relationship.
11. The testing system set forth in claim 10 in which said first
means responsive to first positioning signals includes:
a first positionable means for selectively viewing a narrow
rectangular area on the monitor screen extending between opposite
edges of the monitor screen and forming an optical image
thereof;
a second positionable means for selectively viewing a narrow
rectangular area of the image formed by the said first positionable
means.
12. The testing system set forth in claim 10 in which said third
means interposed between the first and second means includes;
an adjustable lens system for focusing the image formed by the said
first means at the said second means.
13. The testing system set forth in claim 10 in which said second
means for providing electric signals corresponding to the image
formed by the first means includes:
a video camera for viewing the image formed at the said first means
and providing an electric signal representative thereof;
a narrow aperture light detecting means for viewing a small area of
the image formed at the said first means and providing electric
signals indicative of the presence of light at the small area
viewed; and,
switching means responsive to third electric control signal for
providing signals from the said camera or the said light detecting
means.
14. An automatic front of screen adjustment and testing system for
automatically adjusting and testing a television monitor
comprising:
a robotic test stand for receiving and holding the monitor being
adjusted and tested, said stand including a plurality of tools for
engaging adjustable electric circuit components of the monitor, and
adjusting said components under control of control signals, a power
supply for energizing the monitor, and circuits for applying
control signals to said tools and video signals to the video input
of the monitor resident in the test stand;
an image acquisition unit positioned proximate the monitor in the
stand, said unit including, a first positionable means for
selectively viewing, in response to a first electric control
signal, a narrow rectangular area on the monitor screen extending
between opposite edges of the monitor screen and forming an optical
image thereof, a second positionable means for selectively viewing,
in response to a second control signal, a narrow rectangular area
of the image formed by the said first positionable means and
forming an optical image thereof, a video camera for viewing the
image formed on said second positionable means and providing
electric signals representative thereof, light detecting means
arranged to view a small area of the image formed on said second
positionable means and providing electric signals indicative of the
light intensity of the viewed area, and switching means responsive
to a third electric control signal for selectively providing
signals from said camera and said light detecting means as a
function of the state of the third control signal, an adjustable
lens system for focusing the image formed on the second
positionable means on the camera and the light detecting means in
response to a fourth electric control signal; and
a program controlled processor connected to said robotic test stand
and to said image acquisition unit for sending video test patterns
in the form of video signals and control signals to said robotic
test stand and control signals to said image acquisition unit and
for receiving the electric signals from the camera or light
detector of the image acquisition unit, said program controlled
processsor alternatively providing video and control signals to
said robotic test stand and receiving signals from said image
acquisition unit until the signals from said image acquisition unit
and the video signals supplied to the robotic test stand for
application to the monitor bear a predetermined relationship to
each other or "n" iterative cycles have occurred without achieving
the predetermined relationship.
15. A method of adjusting the image control circuits of a
television monitor comprising the steps of:
(1) displaying a predetermined image on the screen the TV monitor
to be adjusted;
(2) defining a plurality of unique areas on the monitor screen,
each said area covering a small portion of the monitor screen;
(3) viewing a first predetermined selected area of the monitor
screen;
(4) analyzing the image viewed in the said first area to determine
the deviation of the viewed image from a predefined image;
(5) adjusting at least one image control circuit element as a
function of the results of the analysis;
(6) repeating steps 2, 3 and 4 until the deviation of the viewed
image from the predefined image falls within acceptable preset
limits provided the occurrence of said event does not exceed a set
number of repetitions of this step 5; and,
(7) viewing at least one additional unique area and for each said
additional unique area viewed repeating steps 2, 3 4 and 5 as set
forth above.
16. The method set forth in claim 15 in which each small area is
approximately one square inch.
17. The method set forth in claim 16 in which the image displayed
on the monitor screen includes a thick bar and two thin lines
displaced therefrom and the analysis determines the displacement of
the bar from the center of the viewed area.
18. The method set forth in claim 16 in which the image displayed
on the monitor screen is a plurality of parallel lines and the
analysis determines the displacement between a line and adjacent
lines on either side of the said line.
19. A method of adjusting the image control circuits of a
television monitor comprising the steps of:
(1) displaying a predetermined image on the screen of the TV
monitor to be adjusted;
(2) viewing at least one area having a diameter of 1 milimeter or
less on the monitor screen; and generating a signal indicative of
the illuminated state of the monitor screen;
(3) continuously adjusting a predetermined circuit element in the
monitor until the viewed area of the monitor screen is illuminated;
and
(4) selecting another area and repeating steps 1 to 3 as required
for adjusting all of the required circuit elements.
Description
PRIOR ART
Television sets and television monitors are manufactured from
components and sub-assemblies which due to the manufacturing
process and tolerances selected to provide economical products
result after assembly in a range of image reproductions, many of
which would be, from the user's point of view, unsatisfactory. In
order to utilize these less than perfect components and
sub-assemblies, adjustable circuit elements such as adjustable
potentiometers are included in some of the circuits.
After assembly the set is energized and test patterns are applied
to the video input. In most instances, the test patterns are
distorted due to circuit variations within the tolerances described
above. In a typical adjustment an operator utilizes a sequence of
images and adjustments in an attempt to obtain a satisfactory
(minimum distortion) image.
This technique has two very distinct disadvantages. It is a slow
labor intensive activity and therefore contributes substantially to
the total cost of the assembly. In the second plate the adjustments
result in a broad range of image quality or distortion due to
differences in the skill or dedication of the individual making the
adjustment.
Attempts have been made to automate some of the steps or part of
one or more steps in the adjustment process; however, applicants
are not aware of any totally automated process which does not rely
in whole or in part on the subjective interpretation by an operator
of the efficacy of the adjustments to produce a consistent,
acceptable distortion free image.
SUMMARY OF THE INVENTION
The invention contemplates a system for automatically adjusting the
operating circuits of a television set or monitor to reduce image
distortion to an acceptable level, said system including: a
computer for generating a sequence of images for application to the
video equipment being adjusted; a scanner for viewing selected
portions of the video image on the set under control of signals
from the computer and providing signals specifying the image viewed
to the computer which generates under program control signals for
manipulating a robotic means for adjusting one or more circuit
components of the set in accordance with the control signals
provided by the computer. Each of the images of the sequence is
selected to test for one or more types of image distortion and the
scanner is positioned to view selected portions positioned about
the screen and provide signals indicative of the viewed image for
analysis which analysis indicates a corrective action to robotic
circuit adjustment means whereby a sequence of images, measurements
and adjustments is utilized to conform the image to an acceptable
pattern without human intervention.
An object of the invention is to provide an automated television or
monitor image adjustment system which operates without subjective
human judgment.
Another object of the invention is to provide a novel method for
adjusting the quality of an image provided by a television set or
monitor.
A further object of the invention is to provide a novel scanner for
use in an automated television or monitor image adjustment
system.
The foregoing and other objects, advantages and features of the
invention will become more apparent from the detailed description
set forth below taken in conjunction with the drawings illustrating
the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of an automated television or monitor
image adjustment system constructed in accordance with the
invention;
FIG. 2 is a detailed schematic diagram of a novel scanner or image
acquisition unit constructed in accordance with the invention;
FIG. 3 is a flow chart illustrating the overall system
operation;
FIG. 4, including FIG. 4A and FIG. 4B, is a detailed flow chart
illustrating the individual steps in the adjustment/inspection
process; and,
FIGS. 5-14 illustrate the images displayed on the screen of the
monitor being adjusted and tested.
DETAILED DESCRIPTION OF THE INVENTION
In FIG. 1 the set 10 under test and adjustment is connected to a
robot and test stand unit 11. Unit 11 is provided with n tools
t.sub.1 -t.sub.n illustrated schematically. Typically, these tools
are screw drivers, each of which engages one potentiometer or other
adjustable circuit element on the monitor and in response to
control signals will perform a rotational adjustment in one of two
directions, i.e., increase or decrease the potentiometer resistance
depending on the direction chosen. In addition to the tools, the
unit 11 provides power to the monitor 10 and video and control
signals which it receives from a control processor 12.
The processor 12 is of conventional design and any general purpose
digital processor may be utilized to perform the functions
described provided the unit has sufficient memory and computational
power. As indicated in FIG. 1, the processor has stored in memory
(which may include disk storage) image information which is applied
to the unit 11 and thence to the monitor 10 via cable Io. The
particular image selected is controlled by a test process program
also stored in the computer memory. As is the case with the images,
only those program steps actually being executed need be stored in
the computer read/write memory. The other steps or modules in the
case of the program and images in the case of the patterns can be
resident in virtual storage on the disk and accessed when and as
needed.
An image acquisition unit (IAU) 14 is positioned so as to view the
monitor screen and the image displayed thereon. The IAU 14 is shown
in greater detail in FIG. 2 and has three controllable elements
which respond to control signals from the processor 12 via cable
IAUC. These signals are part of the test process and are related to
the particular test and/or adjustment related to the specific image
being displayed on the monitor screen.
In response to two of the control signals, the IAU 14 views a small
selected portion of the monitor screen and via a camera 14C shown
in FIG. 2 provides a digitized image of the small portion viewed
over cable Ii. The third signal element provided over the cable
IAUC controls a lens system 14L in light path between the screen
and the camera. The control of the lens system 14L compensates for
the variable distances between the camera and the screen.
These corrections are calculated in advance for each image
displayed and viewed. The focus correction described above will
differ for each size or type screen being used. If the equipment is
to be used for different monitors, the parameters for each can be
stored on the disk and the proper ones selected via set-up
information keyed into the computer before a production run is
initiated. Alternatively, they can be dynamically selected if
intermixed production is used. This will require inputting
information, identifying the type of screen being adjusted and
tested before the test and adjustments are initiated. A simple bar
coded label on the monitor or its carrier with an automatic
scanning device such as is commonly used in supermarkets can
provide the necessary information to the processor automatically
when the monitor is first brought into the test and adjustment
station. Another technique which would eliminate the scanning
operation is to have a pre-programmed sequence and inform the
processor in advance of the types and the sequence. While this is
more complicated and prone to error, it is nevertheless less
expensive to implement.
To this end, FIG. 1 illustrates an external communication line for
receiving this type of control information from a central control
processor, not shown, and for supplying status information relative
to the adjustment and test, i.e., pass/fail information, range of
adjustments, etc., all of which may be utilized by the central
control processor for executing manual rework of rejected units
and/or retuning other elements of the production line.
The digital image information and/or photo multiplier tube (PMT)
output from the IAU 14 is applied to an image processing module in
the processor 12 for analysis. That is what kind of distortion or
deviation is present in the digitized image. Stated differently,
what are the differences between the image applied to the monitor
10 and the actual image seen by the IAU camera 14L. Based on these
differences, an adjustment control module provides image correction
signals via a cable Ic to the robot and test stand 11. These
signals, depending on the specific test and the results of the
image processing, will control the robot to adjust one or more
potentiometers by activating one or more tools t1-tn.
After the adjustments ordered are completed, another view of the
image on the screen is received by the image processing module to
determine the effectiveness of the adjustment. In those instances
where adjustment fails to correct the image, the unit 10 is
rejected and a message dispatched to the central control processor
which will cause that monitor unit to be switched to a manual
rework station further on in the assembly line conveyor.
In FIG. 2 the digital control signals on cable IAUC are converted
to analog signals by a control unit 14R and applied to a "Y" axis
deflection unit 15 which deflects an elongated mirror 16 so as to
view a narrow area extending horizontally from one side of the
screen to the other. They are also converted to analog signals
which are applied to an "X" axis deflection unit 17 which deflects
a mirror 18 so as to view a narrow area on the mirror 16. The
composite view as seen on mirror 18 is focused on the camera 14C by
the lens system 14L. As previously described, the third signal
received from the processor 12 adjusts the focus to take into
account the physical location of the viewed area on the monitor
screen. As is well known, the monitor screen is not flat, in fact
it is convex, and hence the focus varies widely as a function of
the displacement of area viewed from the central region of the
screen. In addition, the mirror acts as a point collector and as
the desired path approaches the edges of the tube, the path length
increases as a function of angular displacement from the normal
position. However, for any monitor tube the total deviation can be
calculated in advance (or dynamically if desired) for each of the
areas to be examined and applied as a focus correction factor to
the lens 14L via a mechanical control unit 19 under control of the
control circuit 14R which provides the necessary digital to analog
conversion to provide a suitable signal for the unit 19.
A member 20 positioned between lens 14L and camera 14C, which may
take the form of a mirror positioned under control of control
circuit 14R can deflect the image to a photo multiplier tube 21 or
allow the image to impinge directly on the photo sensitive surface
of camera 14C. Alternatively, if sufficient illumination is
present, a half silvered mirror may be used and the control unit
14R selects the appropriate output under control of the processor
12.
The flow chart illustrated in FIG. 3 is a high level system chart
showing the basic system steps. The test station first detects that
a monitor is available and that the processor 12 has received and
loaded the monitor type information. Next the parameter tables
associated with the identified monitor are accessed. These
parameter tables include the required tests, set-up sequences and
tolerances, physical characteristics and distortion tables and the
focus table. These elements will become more apparent in the
description of FIG. 4 which follows.
The following step is the performance of the setup which yields the
pass/fail information which is sent to the central processor or
host system. The final step is to clear the test station and await
the next monitor.
FIG. 4 is a detailed flow chart of all the detailed process steps
required to practice the invention and must be viewed in
conjunction with FIG. 3 which illustrates the overall process. The
test parameters for the monitor resident in the test station are
stored in processor memory and are accessed in a predetermined
sequence under control of a pointer 30 illustrated schematically
which may be, as is well known in computer art, a counter which is
incremented, as will be described below, and points to the address
in memory where the appropriate test parameters are stored.
The first step in the process is to access the test parameter
indicated by the pointer 30. The parameters indicate the data
required and the requirements are evaluated. As a result of the
evaluation, the necessary pattern (part of the test parameters) is
sent to the monitor for display. The mirrors 16 and 18 are adjusted
to view the appropriate section of the monitor screen and the lens
is adjusted to focus the viewed image area defined by the angular
position of mirrors 16 and 18.
At this time the camera is read and the image information acquired
and stored in the processor memory. The image data is next
analyzed. Following analysis a determination is made if the
measured parameters fall within gross limits. Images outside of the
gross limits cannot be successfully adjusted and when this is
detected, a fail status message is sent to the central processor
and the test and adjustment cycle is terminated. If the measured
parameters are within the gross limit, they are examined to
determine if they are within the tolerance band or limits.
If they are, this phase of the test is completed except for
housekeeping functions. The data concerning this test step is
collected in a file which is used for off-line analysis of the
system at a later time. The pointer 30 which points to the next
step or operation is incremented. The next operation is examined to
determine if it involves an adjustment or check, if it is one or
the other, the process loops back to the first step for the next
test. If not, it indicates a completion of the test and adjustment
operation and the status is sent to the central processor or
host.
In those instances where the measured parameters fall outside of
the tolerance band, the step is examined to determine if a check or
adjustment is called for. If the step is a check, the unit is
failed and status sent to the central host. If, on the other hand,
the step calls for an adjustment, the required adjustment is
determined from the test parameters and the adjustment made. A loop
count which is one of the gross parameters is incremented. Thus,
after n unsuccessful attempted adjustments the unit will fail the
gross parameter test and thus fail. The process at this, following
this adjustment, loops back to recheck the measured parameters.
The routines described above are repeated for all of the
adjustments and checks required. The actual number of adjustments
and/or checks will vary from one monitor to another and whether the
monitor is color or monochrome.
The patterns illustrated in FIGS. 5, 6 an d7 are used in
conjunction with the camera or the PMT to adjust vertical
parameters. A similar set, not shown, rotated 90.degree. is used to
adjust horizontal parameters. Since the vertical and horizontal
parameter adjustments are very similar, only the vertical will be
considered in detail. The patterns illustrated in FIGS. 8, 9 and 10
are used in conjunction with the camera to check the images for a
pass/fail evaluation and are not intended to be used in an
adjustment operation.
The dotted line rectangles and the circles illustrated in the
illustrations of the patterns indicate various images viewed by the
camera and areas viewed by the PMT, respectively. The pattern
illustrated in FIG. 5 uses a wide solid bar 50 and two thin solid
lines 51 and 52 displaced therefrom at the top of the screen. A
similar pattern is displayed at the center of the screen and
another pattern in which the thin lines appear above the wide solid
line is displayed at the bottom of the screen. The mirrors are
adjusted so that, at different times, the camera views the images
formed within the rectangles illustrated in dotted line.
The pattern illustrated in FIG. 6 includes three narrow solid lines
at the top center and bottom of the screen. The mirrors are
adjusted to cause the PMT to view, at different times, the screen
areas identified by the circles 54. The pattern illustrated in FIG.
7 is a series of equidistant parallel narrow solid lines extending
from the top to the bottom of the screen. Again the dotted line
rectangle indicates an image viewed by the camera.
FIGS. 8, 9 and 10 are self-explanatory and illustrate patterns
which can be used to check:
row straightness
column straightness
north/south pincushioning*
east/west pincushioning*
trapezoidal distortion
parallelism
convergence
linearity*
centering*
These patterns and the images provided by the camera and the
information from the PMT will be described below in connection with
the description of FIGS. 11-14.
The pattern illustrated in FIG. 5 consists of three copies of a
basic pattern which includes a fixed solid line, called a primary
region, a thin solid line spaced therefrom called a secondary
region, and a second thin solid line called a tertiary region. This
pattern is replicated three times in FIG. 5 but inverted at the
bottom of the screen. The thickness of the bar and the spacing of
the thin region is derived empirically from a consideration of the
particular monitor characteristics; typically the primary region is
one character block thick in the instance of a monitor.
The camera is focused on an area of approximately 1".times.1".
However, in a model which was constructed an area 1".times.0.8" was
used, rather than an absolute square. If the monitor parameter
being inspected or adjusted is correct, that is, within
specification, the primary region would lie in the center of the
area viewed by the camera. Depending on whether a primary region, a
secondary region or a tertiary region or nothing is viewed by the
camera, different actions are taken and will be described
below.
If a primary region is found within the field of view, the system
attempts to center it using a centroid offset technique. If a
secondary or tertiary region is found, the direction of the offset
is known and the centroid offset for this region can be calculated.
Once calculated, the adjustment is applied in an attempt to bring
the primary region to its nominal position. In those instances
where no regions are found within the area viewed, the direction of
the offset is known. The relevant potentiometer or adjusting device
is turned a default amount which has been empirically derived and
the area re-inspected. The size of the potentiometer or circuit
adjustment determined from empirically derived sensitivities of the
front of screen effect to circuit control rotation and the centroid
offsets derived therefrom. Areas are used to distinguish regions
from each other and region centroids are used to determine how far
from normal a parameter is.
FIG. 11 illustrates twelve different camera images which can result
from viewing the pattern illustrated in FIG. 5. These have been
labeled E0 to E4 and A0-A6. In these images the dashed lines
indicate invalid data, that is, the bar or line is not fully
contained (in the illustrated case) vertically within the image
area. The twelve images illustrated in FIG. 11 are grouped into two
groups. The E group labeled E0 through E4 and the A group labeled
A0-A6--in general it is possible to exit from an adjustment if one
of the E group of images has been acquired, processed, and the bar
satisfies certain conditions. This occurs usually when the E0 image
has been acquired. On the other hand, if any of the A group images
have been acquired, an adjustment is either required or a fail
condition has occurred.
The pattern illustrated in FIG. 5 includes as previously described
a thick bar and two thin lines spaced therefrom. The thick bar in
the discussion which follows will be identified as a primary
region. The immediately adjacent thin line, a secondary region, and
the thin line furthest removed from the bar is a tertiary region.
Thus, each of the three segments illustrated in FIG. 5 includes the
primary, secondary and tertiary region. With respect to images, A0,
A2, A3 and A5, the secondary region has been identified with
certainty. The offset of the secondary region from its nominal
position can thus be determined and a compensating adjustment made
or a fail/pass decision can be made if a correction is not
effective. In the case of images, A1 and A4, no valid region has
been identified and in both cases an assumption is made that the
non-valid region closest to the primary region's nominal position
is the primary region. The offset from the nominal is determined
and an adjustment is performed or a fail/pass decision is made. In
the case of A6, the image acquired contains neither valid nor
invalid regions and in this case it is assumed that the secondary
region is perfectly centered in the image area. An offset is
calculated and an adjustment is performed, or a fail/pass decision
is made. It should be noted that the sign of the adjustments is
opposite to those utilized for images A0 to A3 and A5.
The objective when performing an adjustment is to adjust specific
parameters of the primary region. There may also be conditions with
respect to the secondary and tertiary regions. These conditions
generally involve their absence. The parameter of the primary
region which is the significant parameter is the position of
centroid of the primary region. The primary objective in processing
the E group images is to center the primary region by determining
the centroid of the acquired region and its offset from the nominal
or centered position, then performing a physical adjustment via the
robot to center the primary region within the viewed area of the
image.
There are three possible views of the parameter adjustment. The
first view is that the parameter is correctly adjusted. This
corresponds to a sub-set of the E group of images in which the
primary, secondary and tertiary regions satisfy all requirements
for that parameter. In most instances this is achieved when the
image E0 has been acquired and the primary region has appropriate
or correct characteristics. The second state involves where the
parameter is not properly adjusted and requires adjustment or
setup. This state corresponds to any of the eight groups of images
which have been acquired. It also corresponds to any of the E group
of images in which the primary, secondary or tertiary regions do
not satisfy the requirements of the specification. The third state
is where the parameter is in adjustment or has been properly set up
but has interaction. This state corresponds to the condition where
an adjustment is being performed which has an effect on the state
of another parameter. Examples are those of height and vertical
linearity. When both of these parameters are correctly adjusted, or
set up, an E0 type image with conditions on the primary region is
expected. However, in order to successfully decouple the
adjustments, linearity must be adjusted first. The state of the
height parameter is therefore a variable. This may be translated
into the condition that when setting up linearity the only
predictable parameter is the position of the primary region, thus
no constraints should be placed on the secondary and tertiary
regions.
Adjustment techniques based on the PMT output are useful for the
parameters which include width, horizontal linearity or
alternatively horizontal centering, east/west pincushioning,
height, vertical linearity or alternatively vertical centering and
north/south pincushioning. When the PMT is used to make
adjustments, the adjustment process is considered a closed loop
with continuous feedback. That is, the output of the PMT is not a
sample output. This eliminates the need for iterations in setting
up the parameter. This technique is tolerant of manufacturing
errors, thus if potentiometers of incorrect value have been
inserted in the particular monitor under test, and the correct
front of screen parameters are still achievable, the technique will
work with very little cycle time impact. In addition, the technique
does not require analysis of large amounts of data such as are
contained in an image in order to verify that an adjustment is
being performed correctly; therefore, cycle time is essentially
independent of the preset of the circuit elements.
There are prerequisites to this adjustment technique. One, the
adjustment direction must be known. This direction may be derived
from the previously described images. Therefore, the potentiometer
or ciruict element can be turned in the correct direction to
achieve adjustment. Secondly, the photomultiplier tube must be able
to sample a spot having a maximum diameter of 1.0 millimeters at
any desired place on the face of the monitor. The structure
described is fully capable of accomplishing this.
The adjustment technique involves focusing the photomultiplier tube
on the monitor screen at a specific point for a specific parameter
adjustment, displaying a line such as those illustrated in FIG. 6
on the monitor, and turning the relevant circuit element until the
line lies in the field of view of the photomultiplier tube.
The sequence is as follows: (1) The pattern shown in FIG. 6 is
displayed on the monitor. (2) The photomultiplier tube is pointed
at and focused on one of the points indicated on the screen for a
particular adjustment. (3) The photomultiplier tube output is
sensed to detect the presence of light on the sensor, the relevant
circuit element or potentiometer is turned to effect the adjustment
and (5) when the photomultiplier tube output fires the
potentiometer is no longer turned and the adjustment has been
completed.
After one of these adjustments has been made, a camera-based
technique, as described previously, may be used to check the
parameter after adjustment.
The pattern illustrated in FIG. 7 may be utilized for adjusting the
linearity of the monitor under adjustment and test and the image
provided by the camera when viewing the pattern of FIG. 7 is
illustrated in FIG. 12. In this instance the linearity
potentiometer is adjusted until the distance between any of the
three lines illustrated in FIG. 12 is within linearity
specifications and larger than an empirically derived minimum. The
pattern and line spacings are derived from considerations of the
adjustment characteristics of each monitor type. The direction of
the adjustment is derived from a comparison of the distances A and
B identified in FIG. 12. If A is larger than B, then the adjustment
is in one direction. If B is larger than A, the adjustment is in
the opposite direction. The size of the adjustment is derived from
a consideration of the ratio of A and B.
The pattern illustrated in FIG. 8 has several uses. The different
areas viewed are identified by numerals in FIG. 13 while FIG. 14
illustrates the use of the patterns shown in FIGS. 9 and 10. All of
these are used for checking the monitor to determine whether or not
the image quality meets the specifications set for a particular
monitor.
The patterns and images are used in the following way. The first
check utilizes the images illustrated in FIG. 13. The first
parameter checked is image tilt. This utilizes images number 3 and
4 and determines the centroid offset in one axis and hence the
angle of tilt. The check for trapezoidal distortion uses images 1,
2, 5 and 6 and measures the centroid of the illuminated area to
determine trapezoidal distortion. Using a similar technique,
parallelism is checked by using images 1, 2, 5 and 6. Centering of
the images is checked by using image number 7 and computes the XY
centroid offset of the illuminated area. Convergence of the color
images is also checked by using some or all of the images
available. This check requires the pattern being displayed
sequentially in each of the three primary colors, then the
centroids of each of the color images are compared for
deviation.
A second set of checks utilizes the images illustrated in FIG. 14.
These images are numbered 1-15 and one of the images in the upper
left-hand corner bears two numbers. Images 1-10 are acquired when
the pattern illustrated in FIG. 9 is displayed and images 11-15 are
acquired when the pattern illustrated in FIG. 10 is displayed.
North/south pincushioning check uses images 1, 5 and 10. The offset
between the centroids of these images in one axis indicates the
amount of pincushioning present in the north/south direction. Row
straightness uses images 1-10. This test utilizes the deviation of
the centroids of the images in the range of 1-10.
Images 11, 13 and 15 are used to check east/west pincushioning and
the offset between the centroids of these images in one axis
indicates the amount of pincushioning present in the east/west
direction. Column straightness is checked by using images 11-15.
This check is very much similar to that used for row straightness,
described above.
The order in which the front of screen adjustments occur may differ
slightly from one monitor or TV set to another. However, the
following sequence has been found to be particularly useful: (1)
preset contrast, (2) set brightness, (3) set horizontal centering,
(4) set vertical parameters, (4A) linearity, (4B) centering, (4C)
height, (5) set horizontal parameters, (5A) width, (5B)
pincushioning, (6) set brightness, (7) check parameters. The checks
may be performed in any sequence.
While a single embodiment of the invention has been shown and
described in detail, it will be obvious to those skilled in the art
that many changes and modifications may be made without departing
from the spirit and scope of the invention.
* * * * *